An airline is utilizing a nested three-tier fare structure, $200, $250, and $300. The capacity of this airline is 30 seats. The probability of at least n passengers willing to buy different levels of tickets is different and summarized below: P(x>=n) = 1-x/30, when the ticket fare is $300 P(x>=n) = 1-( x/30)^2, when the ticket fare is $250 a. What is the booking limit of three fare classes?